unslothai/unsloth · error · CodexTransportError

Could not reach ChatGPT Codex.

Error message

Could not reach ChatGPT Codex.

What it means

Raised when an httpx.HTTPError (connect failure, DNS error, TLS error, read timeout) occurs, the response was never yielded, and the attempt counter has reached _MAX_TRANSIENT_RETRIES. It is the terminal 'cannot reach the endpoint at all' error after exponential backoff (2**attempt seconds between tries).

Source

Thrown at studio/backend/core/inference/openai_codex_client.py:414

                        yield None
                        return
                    continue
                if response.status_code == 429:
                    raise CodexQuotaError(
                        "ChatGPT subscription quota is temporarily unavailable.",
                        status = 429,
                        metadata = _quota_metadata(response),
                    )
                suffix = f" {detail}" if detail else ""
                raise CodexTransportError(
                    f"ChatGPT Codex request failed ({response.status_code}).{suffix}",
                    status = response.status_code,
                )
        except httpx.HTTPError as exc:
            if yielded:
                raise
            if attempt >= _MAX_TRANSIENT_RETRIES:
                raise CodexTransportError("Could not reach ChatGPT Codex.") from exc
            await _retry_pause(float(2**attempt), cancel_event)
            if cancel_event is not None and cancel_event.is_set():
                yield None
                return
    raise CodexTransportError("Could not reach ChatGPT Codex.")


class OpenAICodexClient:
    def __init__(
        self,
        access_token: str,
        account_id: str,
        *,
        refresh_access: Callable[[], Awaitable[tuple[str, str]]] | None = None,
    ) -> None:
        self._token, self._account_id = access_token, account_id
        self._refresh_access = refresh_access
        self._client = _create_http_client()

View on GitHub (pinned to 203007d190)

Solutions

1. Verify network egress to the Codex endpoint (curl/DNS lookup) from the same host
2. Check firewall/proxy/VPN rules for the endpoint domain
3. If truly transient, catch CodexTransportError with this message and retry later with a longer outer backoff

import httpx, socket

def codex_endpoint_reachable(base_url: str) -> bool:
    host = httpx.URL(base_url).host
    try:
        socket.gethostbyname(host)
        return True
    except socket.gaierror:
        return False

try:
    async for chunk in stream:
        ...
except CodexTransportError as exc:
    if 'Could not reach ChatGPT Codex' in str(exc):
        await offline_backoff_then_retry(request)  # long outer backoff
    raise

When it happens

Trigger: Every attempt in the retry loop raises httpx.HTTPError before a response arrives: DNS resolution failure, connection refused, TLS handshake error, or read timeout — with attempts exhausted.

Common situations: Offline machine; firewall blocking egress to the Codex endpoint; DNS misconfiguration; VPN dropped mid-session; endpoint temporarily unreachable for longer than the full backoff window.

Related errors

• Could not refresh ChatGPT authorization. Please retry.
• VirusTotal upload failed after {attempts} attempt(s): {last_
• ChatGPT credential update is busy. Please retry.
• Could not reach ChatGPT authentication.
• ChatGPT returned an invalid authorization response.

AI-assisted analysis of unslothai/unsloth@203007d190 (2026-08-15). Data as JSON: /api/errors/a42b9e9bfc053517. Report an issue: GitHub.